A UICC card (a chip card materially defined in standard ISO 7816-X) of the SIM type (short for Subscriber Identity Module in English) or USIM (short for Universal Subscriber Module in English) conventionally memorises personal data and applications. The majority of USIM cards only provide access to data or applications once the user has entered a personal identification number (PIN) of the chip card. A counter formed in a non-volatile memory of the UICC card memorises the number of incorrect entries of the PIN of the chip card and the maximum permitted number thereof. The method of entry of the PIN of the chip card is blocked and with it the card, when the number of incorrect entries is equal to the maximum permitted number. Reinitialisation of the counter is performed either when a valid PIN of the chip card is entered before blocking or when a PIN unblocking code (PUK—PIN Unblock Key) is entered after blocking. Entry of the PUK after blocking unblocks the UICC card.
In practice, a user only infrequently uses the PUK associated with the chip card PIN. Therefore, when his/her UICC card is blocked, he/she generally does not have any PUK code available, because it is not memorized for example or because he/she has mislaid the certificate mentioning the PUK. The majority of telephone operators have set up telephone platforms designed to provide the user of the UICC card with a PUK code. The user often does not have the telephone number of the platform of his/her operator available. Furthermore, these platforms are costly and require means of identification of the user in order to avoid providing a PUK to a trickster.
UICC cards (and digital devices in general) present an increasing number of applications safeguarded by a application personal identification number (hereafter known as the application PIN) and sometimes developed by a company other than the telephony operator issuing the UICC card. Since each of these applications may present a specific application PIN and a PUK code, the user does not have all these date available in practice in case of need. The telephone platforms are more complex to organise in this case, with each company being required to memorize a databank for the PUK codes of its application.
The user must furthermore identify which platform to contact in order to unblock the UICC card. For these various reasons, a large number of applications are not locked by an application PIN.